Process for extracting metallic nickel



Patented May 22, 1928.

UNITED ST T S PATENT OFFICE.

AHABON' BAGHDAS AR BAGHD ASABIAN, NOW BY JUIJICIAL CHANGE OF 'IAKE BYSAB BAGSAB, OI HUNTINGTON, WEST VIRGINIA.

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This invention is an improvement in processes for extracting nickel and has for its object to provide a process by means of which the nickel can be extracted, as metallic nickel, from nickel-bearing solutions ,and from ores, mattes, speisses, and alloys of nickel. My is very suitable for recovering nickel from nickel-bearing solutions which are produced in copper refineries in the course of electrolytic refining of cop- In treating ores, mattes, speisses, calcines, alloys, and other materials for the extraction of the nickel, m process consists in dissolving the materia to be treated for nickel, by means of a solvent, such as an acid or aclds, or a solution of a salt containing-dissolved chlorine gas, or by means of any other suitable solvent; in replacing or precipitating bmeans of metallic nickel the noble metals, copper, etc., which may be present in the resulting solution; in precipitating the iron, if this be present, from the solution by means of zinc oxide, which precipitate will carry with it by occlusion practically all of the arsenic and antimony; in precipitating from the solution thus purified the nickel as .metallic nickel by means of metallic zinc or by blue-powder and in preparing a marketable form of a zinc salt.

The nickel solutions which are produced in copper refineries in the course of electrol 'tic refining of copper, contain sulfuric acid, some arsenic and antimony, and a trace of iron. In treating such solutions for the recovering of nickel my process is the same as that described above, with the exception that the acid present in such solutions has to be almost completely neutralized by a suitable acid consuming material, such as zinc oxide, limestone, etc., before the complete precipitation of the nickel may beeffected by means of metallic zine,

I have found that under proper conditions, which will be described below, metallic zinc, or a mixture of zinc and z inc'oxide or blue powder precipitates practically completely all of the nickel as metallic nickel from neutral or slightl basic nickel-bearing solutions.- Some mcke may be precipitate by means of zinc from acid solutions also, but in the latter case the precipitation of the nickel is not complete, since most of the zinc Application the July 19,

keeping find that only a slight excess of zinc will be 1928. Serial I0. 188,600.

The precipitation of metallic nickel by means of metallic zi c may be represented by the following ch nical equation in which mckelous chloride is taken as an example:

NiCl,+Zn=ZnCl,-l- Ni.

My experiments show that zinc precipitates nickel from solutions very rapidily if the temperature of the nickel-bearing solution is raised somewhat; at ordinary temperatures the re-action is slow. The temperature range about from 0 C. to about 90 C. or higher, gives satisfactory results. Generally speakmg, the higher the temperature of the solution, the faster is the react-ion.

I have found that zinc preci itates nickel somewhat faster from chlori e or nitrate solutions than from the sulfate solution; and that the addition of a soluble chloride or nitrate to a sulfate solution accelerates the recipitation or deposition of the nickel. As ar as the completeness of the reaction is concerned, a sulfate solution behaves in a manner similar to the nitrate or chloride solutions.

Besides the temperature at which the reaction is carried out and the kind of the solution used, another factor which influences the rate of deposition or precipitation of nickel from solutions is the physical condition of the metallic zinc used to bring about the precipitation. I find that although zinc in the vform of slabs, sheets or shots precipitates nickel from solutions, better results are obtained by using granulated or powdery.

zinc, or blue powder.

In order to assure an almost complete depletion of the solution from nickel, I find that it. will be advisable to use an excess ofzinc. However, in experiments show that better results are 0 tained and less zinc is required to precipitate practicall all of the nickel, if

the necessary amount. 0 zinc is added to the solution portion by portion at intervals and not all of it at onceat the; start of the run.

Followingmthis method of procedure and b e solution stirred or agitated,

regpgired to precipitate practically all of the nic el from the solution.

If the solution is fairly high in nickel or 5 to recover all if it is desired to obtain a nickel precipitate which is almost free of zinc, I find it advisable, although not absolutely necessary, to carry out the precipitation of nickel by means of zinc, in two successive steps. The first operation or step consists in adding to the nickel-bearing solution somewhat less zinc than that required for the complete precipitation of all of thenickel present in the solution, and in keepin the solution stirred or agitated until practically all of the zinc is used up to recipitate the nickel. At this stage, .a nic el precipitate is formed which is practically free of zinc, and also a solution which still contains some nickel in a soluble form. The precipitated nickel is then removed or separated from the solution by filtration or by other suitable means. During the second operation the solution resulted from the first, step or operation is treated with a large excess of zinc, and the mixture of zinc and solution is eliiciently stirred or agitated until practically all of the nickel is precipitated from the solution by the excess zinc present. A part or all of this nickel-zinc mixture can then be returned to the system for treating new portions of nickel-bearing solutions, and the c cle of operations repeated. By dividing t e process into two such successive operations, a nickel precipitate may be obtained which is racticall free of zinc, and a maximum utilization o zinc may be assured.

If the nickel is present in the solution in the nickelic condition and if it is desired of the nickel as metallic nickel, it would be advisable to reduce this to the nickelous form in a slightly acid solution by means of a suitable reducing agent, such as sulfur-dioxide, or metallic nickel or zinc. It is necessary to do this because nickelic salts decompose in slightly alkali solutions and nickelic hydroxide precipitates which, under ordinary conditions of operations, will not be reduced to metallic nickel by means of' zinc.

The elimination of arsenic and antimony from the solution is advisable, since metallic zincdissblves, although very slowly, even in neutral solutions, liberating nascent hydrogen; the latter may form arsine and stibine gases, if arsenic and antimony are present. If there is suflicient iron present in the solution, arsenic and antimony are practically completely removed from the solution by the precipitated iron hydroxide. In case the solution is short of iron, some iron must be added, preferably in the form of a ferric salt, to the. solution to assure the removal of the arsenic and antimony.

The final products obtained by my process are metallic nickel and a solution which contains zinc in the form of a soluble salt.

The-zine salt may be recovered from the which upon being melted metallic luster.

solution by" any suitable process, such as by crystallization 'or by evaporation, and marketed as such. T e nickel obtained in the precipitated form is black and powdery, I

assumes its usual The nickel thus produced is practically free of copper, but it may contain small amounts of other impurities in. which case it has to be refined. With careful work, however, fairly pure nickel may be obtained by my process.

What I claim is:

1. The process for the precipitation of nickel which comprises treating a nickel bearing solution to remove substantially all objectionable impurities therefrom, adding metallic zinc to the solution to precipitate the major part of the nickel, separating the nickel so precipitated, and adding to the resulting solution maintained at an approximate boiling temperature a quantity of metallic zinc in quantities sufficient to efiect substantially complete precipitation of the nickel content of the solution.

2. The process for the recipitation of nickel which comprises ad mg to the sub stantially neutral nickel solution a quantity of metallic precipitants for the nickel in quantities suflicient to precipitate the major portion of the said nickel, separating the precipitant from the solution, adding a fresh portion of the preci itant to the residual solution to complete y precipitate the remainder of the nickel and utllizing the resulting mixture of precipitated nickel and precipitant for the treatment of fresh quantities of the solution, until substantially all the nickel is obtained free from the precipitated metal.

3. The process for the precipitation of a metal from a solution thereof, which comprises adding to the solution a' metallic precipitant for the same metal in quantities insufiicient for the complete .precipltation of the said metal, separating t e precipitated metal, adding a relatively large excess 0 precipitant to the solution to precipitate the remainder of the said metal and utilizing the resulting mixture of precipitated metal and precipitant for the treatment of fresh quantities of solution until substantially all of the precipitant is dissolved from the mix ture, leaving as a residue the precipitated nletal in substantially pure form. K'

4. The process for the precipitation of nickel from the nickelous solutions which comprises adding to the solutions a quantity of zinc in amounts insuflicient toprecipitate separating and reusing the mixture of pref no 7 adding to the solution a quantity of metallic zinc sufiicient to precipitate the major portion of the nickel, heating the residual solu-. tion to boiling, adding to the boiling solution a quantity of zinc sufiicient to precipi- 10 tate the remainder of the nickel and reusing the mixture of precipitated nickel and zinc in successive nickel operations until the zinc content of the mixture has been removed,

the precipitation being carried out in the 15 presence of nickel nitrate and nickel chloride.

AHARON BAGHDASAR BAGHDASARIAN. 

